You may wonder what makes a diamond so precious. To begin with, it requires nearly 250 tons of ore to be mined and processed in order to create a single, one-carat diamond. Artisans begin with rough stones as large as 150 carats to determine the optimal number of smaller diamonds that can be crafted. During the polishing process, it's common for more than half of the rough diamond to end up as diamond dust.

The transformation of a rough stone into the extraordinary display of brilliance and fire created by a finely cut diamond requires great skill and years of training on the part of the diamantaire (a craftsman who specializes in selecting, cutting and polishing diamonds).

In the diamond polishing process, a lot is sacrificed to yield the most beautiful stone. Striking a balance between size and quality is critical to ensure the greatest value. So the cutting of every diamond must be carefully planned before the stone is marked for sawing.

The rough diamond is sawn in two by a blade impregnated with diamond dust - the only substance that can cut through a diamond. Sometimes more advanced methods are required, such as a computer-controlled laser beam. Next, a bruting machine grinds one diamond against another to form the girdle, the round outer edge of the diamond. And the diamond begins to get its shape.

Skilled diamond polishers then create the diamond facets that give the diamond its familiar shape. The diamond is set into a metal rod, which holds the stone against a spinning wheel impregnated with diamond dust.

Innovative research and state-of-art technology contribute to the ability of diamantaires today to sculpt beautiful diamonds. A modern diamond cut delivers measurably more brilliance than other diamonds of similar quality and grading. That's why if you look at the diamonds in a piece of antique jewelry they may not capture and reflect light as beautifully as a modern cut diamond.

Craftsmanship, precision and attention to detail are required to release the full potential for beauty and fire that lies within each diamond. Anything short of a perfect cut – meaning a diamond that is perfectly proportioned - results in a stone of inferior beauty and brilliance.

Why proportion matters

Well proportioned stones reflect more light, and therefore often appear whiter and brighter than poorly proportioned stones. This can make a well cut diamond look two or three color grades better than it actually is. Similarly, diamonds in perfect proportion may also look better than other diamonds of higher clarity, but which are not as well cut. Here are the terms you need to know:

· Depth percent refers to how deep the stone is in relation to the diameter.

· Table percent is the percent that the flat top facet (the “table”) takes up in relation to the diameter of the stone.

· The Girdle of a diamond is the dividing line between the crown, or top part of the stone, and the pavilion, or bottom part of the stone.

· The Culet , if there is one, is the facet on the pointy bottom part of the stone which helps prevent chipping.

What you need to know about polish

Polish marks are caused by the tiny diamond crystals in the polishing wheels used by the diamond cutters to polish the facets of the diamond after cutting.

Polish is graded into five categories: excellent, very good, good, fair and poor. Excellent means “superior,” not perfect. A diamond can have just a few hard-to-find polish lines or tiny blemishes and still be rated excellent. If a diamond has only faint polish lines or insignificant blemishes, its polish is very good. If a diamond has transparent polish lines which are visible through the pavilion, when a few facets show polish marks or when there are several small blemishes, the polish is good.

Once again – the best judge is your own eyes. You can try for at least good polish. While very good and excellent are nice to have, they are fairly rare and usually not noticeably better than those with a good rating when viewed with the naked eye.

Before you start shopping – beware – understand the 4 myths of diamond cuts

Diamond certification will tell you how the diamond is graded. Understand how to read a diamond certificate.

There are lots of diamond shapes . Which one is right for her? Round brilliant, princess cut diamonds, pear shaped diamonds, emerald cut diamonds, and heart brilliant diamonds. Some of the most popular cuts include radiant cut and princess cut diamonds.

Glossary of terms.